Electromotive drive for calculating machines



Sept. 9, 1924. 1,507,922

M. LIEDL ELECTROHOTI'VB DRIVE FOR CALCULATING MACHINES rum Doc. 24, 1921 v 2 Shun-Shut 1 Fig.1.

ELECTROHOTIVI DRIVE FOR CALCULATING MACHINES Fund Doc. 24, 192) 2 Slutty-8h! 2 Fig.2.

Jnventor:

Patented Sept. 9, 1924;

UNITED STATES MARTIN LIEDL, OF BERLIN-STEGLITZ, GERMANY.

ELECTROMOTIVE DRIVE FOR CALCULATING MACHINES.

Application filed December 24, 1921. Serial No. 524,753.

To all whom it may concern:

Be it known that I, MARTIN LIEDL, of German nationality, residing at 25 Ahornstrasse, Berlin-Steglitz, German have invented certain new and usefu Improvements in and Relating to Eleotromotive Drives for Calculating Machines; and I do hereby declare the following to be a full, clear, and exact description of the invention, of which the following is a specification.

The invention relates to that type of electromotive drives for calculating machines, whereby for each calculatin operation the electric motor is mechanical y coupled with the shaft of the machine. If the machine itself is not used for a longer period, it can happen with this kind of drives that current is wasted in case the attendant omits to cut out the quietly running motor. This ne ligence on the part of the attendant is reuently followed by a rapid wearing out of t e motor and by a fusin of same.

- It has therefore alrea y been proposed to construct the driving mechanism in such a manner that the circuit is automaticall broken when the machine is not being use The characteristic feature of the present solution of the problem known in itself consists in causing the breaking of the current by the electric motor itself in such a manner that after a certain length of time after every actuation of the operating key the armature circuit is broken by a switch element which is excited by the electric current.-

Upon the accompanying drawings an electromotive drive of this type has been shown by way of example, and it is:

F1 1 the general arrangement of the switc mechanism,

Fig. 1, a partial view of the switch elements in a slightly altered position,

Fig. 2, the view of an intermediate position of the switch mechanism, and

Fig. 3 in full lines the view of said mechanism in the position of rest.

The illustrated switch mechanism acts in the following manner:

56 motor.

Fig. 3 shows in the position indicated by thejfull lines the position of rest of the switch mechanism previous to the commencement of the o oration.

The slide 6 y virtue of the sprin 13 rests below with its notch 10 on the sli e pin 12 and above with the snug 7 on the heating element 14.

In this osition the two insulated stop pins 15 an 16 keep the contacts 20 and 21 opened.

If now the lever 2 (Fig. 1) is actuated by the draw rod 1, by means of the roller 5 the slide 6 is first turned about the slide pin 12 until the slide 6 rests against the stop 11 (Fig. 1, position shewn in full lines). Upon a movement of the stop pin 15 mounted on the slide, the contact 20 is closed and the motor is started as such may be seen from the switch board die ram.

When the lever 2 is furt er deflected, the slide 6 turns about the stop 11 until the bottom notch 10 of the slide 6 leaves the slide pin 12.

Under the action of the spring 13 the slide 6 now moves upwards until it strikes against the heating element 1.4 with its edge 7 (Fi 1 osition of arts shewn in dotten lines? ogether wit the slide 6 also the stop pin 16 moves and enables a closing of the contact 21 which controls the circuit passing through the heating element.

The current entering through the base plate 17 passes now through the contact lever 19 and contact 21 to the heating winding 23 of the'heating element 1 1 and causes the latter to be heated. As it consists of two bars of different metal the coefiicients of expansion of which varying very widely from ranged in the right position to each other.

Owing to the pressure which the heating element 14 in consequence of this bending exerts on the slide 6, the latter is moved downward until under the action of the tension spring 13 it drops from the sliding surface 8 moving on the slide pin 12 into the notch 10.

The slide 6 when falling into this oblique position and pressing with its bottom catch on the contact lever 19, pulls the contact 21 apart, whereby the current passing through the heatin winding 23 1s roken.

In consequence t ereof the heating element 14, no longer affected by heat through ually' cool off and thereby tends to return i to its original straightened position from (ill its downward bent shape caused by the heat. This means that in the .present instance the heating element moves with its right hand and free end upwards.

Since the slide 6 owing to its being held fast with its bottom notch 10 by the slide pin 12 cannot make a longitudinal movement, the heating element 14- upon cooling ofi moves along the snug 7 of the slide 6,, until the snug 7 loses its support, and the slide 6 under the action of the tension spring 13 drops now with its upper notch 9 on to bars of the heating element. At this moment the slide 6 by means of its upper stop pin 15 and contact lever18 pulls the contact 20 apart which is followed by an immediate stopping of the motor 22.

The period between the closing of the current or heating respectively and the cooling-ofl of the heating element 1e and the disconnecting of the motor caused thereby can be varied at will within certain limits by means of regulating devices so that the motor continues to run even if great intervals of time lie between two successive ac tuations of the machine.

As long as the slide 6 has not yet dropped from the slide pin 12 into the notch 10 (Fig. 2), the movements caused by the machine key and drawirod 1 on to the pawl 2 with its roller 5 are without effect on to the slide 6.

If however in Fig. 2 the slide 6 with its sliding surface 8' is already fallen from the slide pin 12 into the notch 10, the roller 5 upon an actuation of the machine key only pushes back the slide and closes the heating current contact 21 for. short. periods with-' out the motor contact 20 becoming thereby influenced in any Way.

I claim as my invention 2- 1. In an electromotive drive for calculating machines in combination with a machine kc .and an electric time switch in the circult of the electric motor for automatically breaking the current after a predetermined period from the last actuation of the machine key, a bimetallic member, a heatin coil surrounding said member. and adapted to be switched into the circuit by the actuation of the machine key an automatic switch member to interrupt the heating current and disconnect the motor after the bimetallic member has cooled down, and means in connection with'the said automatic switch member, to prevent the cutting out of the motor as long as the machine key is depressed. I

2. In an electromotive drive for calculating machines in combination with a machine menses key and an electric time switch in the circult of the electric motor for automatically breaking the circuit after a predetermined period from a last actuation of the machine key, a bimetallic member, a heating coil surrounding. said member, an automatic switch member capable of longitudinal and lateral movement relative to the bimetallic member, machine key" operated means to move said switch member, and a pair of contact controlling levers pivoted in fined relation to the said switch member and op erable by catches provided on the latter.

3. In an electromotive drive for calcarlating' machines in combination with a machine key and an electric time switch in the circuit of the electric motor for auto.

matically breaking the current after a predetermined period from a last actuation of the machine key, a bimetallic member, a heating"- coil surrounding said member and adapted to be switched into the circuit by the actuation of the machine key, an automatic switch member comprising a spring controlled slide member, a notch on said slide member, a slide pin to co-operate withsaid notch, a snug on the slide member to engage one end of the bimetallic member, contact-controlling levers in fixed relation to the slide member, and catch pins on the latter adapted to engage said contact actuating levers.

4. In an electromotive drive for calculating machines in combination with an electric motor, a machine key to start the motor, a coupling rod operable by the machine key, a pair ofcontact levers, a bimetallic member and a heating coil surrounding it, a sliding switch member intermediate said coupling rod, the contact levers and the bimetallic member, a pivoted two-arm lever at the end of the coupling rod to move said sliding switch member, a tension spring between the two-arm lever and the said sliding member, means on the sliding member to close the motor and heating circuit when moved into its outermost position, and means also on the sliding member to catch the free end of the bimetallic member and to be repelled by the action of the latter 

